pressure drops in valves
pressure drops in valves
(OP)
I am currently trying to use Hevacomp for general pipesizing. My client prefers the output. Manually I have a clear approach but tedious. When using the software it requests for a K value, fairly ok with this, dimensionless and there are lists from manufacturers. It also requires an acceptable static pressure drop? Both are required for the progression of the software. From experience what would be likely figures for fittings?





RE: pressure drops in valves
K*Rho*V*V/2g
where
rho= density in lb/Ft^3or Newtons/M^3
V fluid velocity Ft/sec or M/sec
g= gravitational constant 32ft/sec^2 or 9.8M/sec^2
The answer is in lb/ft^2 or Newtons/M^2 which can be converted to psi or whatever you Brits use.
For example,
if a globe valve has a K factor of 1.5 , then for a 1 inch pipe size handling 8 gpm of water which corrresponds to 2.5 ft/sec, the
V^2/2g called the velocity head is
.097 feet and at water's density 62.4 and K=1.5 the pressure drop across the valve is
1.5*62.4*.097=9lb/ft^2=.06 psi
I imagine that if you use the mfr K value, they want to make sure that you are accepting that value translated to psi drop as a check. So enter any reasonable acceptable value, say .1 psi and see what the program asks. It may say there is a discrepancy and tell you why. I just don't know.
RE: pressure drops in valves
RE: pressure drops in valves
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RE: pressure drops in valves
RE: pressure drops in valves